Optimizing Power System. Restoration Resources and. Actions. Chen-Ching Liu.
Electrical and Computer Engineering. Iowa State University. PSERC Research ...
Optimizing Power System Restoration Resources and Actions Chen-Ching Liu Electrical and Computer Engineering Iowa State University
PSERC Research Tele-seminar, November 2006
State of the Art • Primarily manual work by operators • Off line restoration planning • Little progress has been made on system restoration methodology • On line implementation limited • Literature 2
System Restoration Stages
Load restoration is only a means to an end
PREPARATION
Actions are time-critical
SYSTEM RESTORATION
Load restoration is the objective
LOAD RESTORATION
30-60 minutes 3-4 hours 3
System Restoration Tasks • Knowing status of the grid • Maximizing generation capabilities with the available black start resources • Scheduling of tasks and resources during system restoration • Establishing transmission capability and paths while meeting operating constraints • Picking up load while meeting operating constraints and load requirements 4
Example Restoration Strategies • Build-upward • Build-downward • Other variations
5
First Stage • Basic operations common to all strategies • Sub-processes defining early stages of restoration process • Minimal configuration of autonomous stable source with necessary transmission
6
Restoration Building Blocks • May include non-autonomous BTG, connection transmission, necessary compensation & load blocks • Associated with schedule of switching & control actions
7
Second Stage Target System • System state achieved by end of restoration process • May not be pre-disturbance system • Restrict set of post-restoration configurations
8
Restoration Constraints • Physical constraints • Scheduling constraints • Policy constraints
9
Third Stage
Load Restoration – Pick Up Loads
10
Restoration Strategy SYSTEM RESTORATION
LOAD MANAGEMENT
MW MANAGEMENT
BLACK-START UNIT OPERATION
MECHANICAL INSPECTION
FUEL INSPECTION
MVAR MANAGEMENT
NON-BLACK-START UNIT OPERATION
MAN-POWER DISPATCH
PATH MANAGEMENT
SWITCHING SEQUENCE INSPECTION
STATIC MVAR INSPECTION FAULT INSPECTION
STABILITY INSPECTION
CAPACITY INSPECTION
TRANSIENT VOLTAGE INSPECTION
11
Example – Generation Capabilities (4 Different Generating Units)
12
Example – Optimal Starting Sequence MW
13
Cranking Priorities • Units with critical maximum interval • Critical max interval units with most urgent time constraint • Units that can generate highest MWH within a given period
14
PECO-Energy Generating Units Unit
Type
Chester_4 Chester_5 Chester_6 Chester_7-9 Conowingo_1-7 Conowingo_8-11 Cromby_1 Cromby_2 Croydon_1 Delaware_7 Delaware_8 Delaware_9-10 Delaware_11-12 Eddystone_1 Eddystone_2 Eddystone_3 Eddystone_4 Eddystone_10 Eddystone_20 Eddystone_30-40 Falls_1-3 Moser_1 Muddy Run_1-4 Muddy Run_5-8 Richmond_3 Richmond_4 Schuylkill_1 Schuylkill_3 S h lkill 10
CT CT CT CT Hydro Hydro Steam Steam CT Steam Steam CT CT Steam Steam Steam Steam CT CT CT CT CT Hydro Hydro CT CT Steam Steam CT
MW Cap. Ramp. rate Crank to paral. Crit. max. int. Crit. min. int. Startup req. (MW) (MW/hr) (hr) (hr) (hr) (MW) 15 40 0 N/A N/A 0 15 40 0 N/A N/A 0 15 40 0 N/A N/A 0 45 120 0 N/A N/A 0 200 200 0 N/A N/A 0 200 200 0 N/A N/A 0 180 80 1:40 N/A N/A 8 180 80 1:40 N/A N/A 8 300 120 0:30 N/A 5:00 6 130 60 2:40 3:20 N/A 5 130 60 2:40 3:20 N/A 5 30 90 0 N/A N/A 0 30 90 0 N/A N/A 0 150 40 1:40 N/A 3:20 12 150 40 1:40 N/A 3:20 12 150 40 1:40 N/A 3:20 12 150 40 1:40 N/A 3:20 12 15 45 0 N/A N/A 0 15 45 0 N/A N/A 0 30 90 0 N/A N/A 0 45 135 0 N/A N/A 0 30 90 0 N/A N/A 0 400 150 0:30 N/A N/A 6.6 400 150 0:30 N/A N/A 6.6 50 100 0 N/A N/A 0 50 100 0 N/A N/A 0 135 135 2:00 2:30 N/A 2.7 135 135 2:00 2:30 N/A 2.7 15 45 0 N/A N/A 0
Ramping RampingRate Rate
Critical CriticalMin. Min.Interval Interval
Critical CriticalMax. Max.Interval Interval ......
15
MW Capability Curves
16
Restoration Strategy with Tie Lines SYSTEM RESTORATION TIELINE LINE TIE UTILIZATION UTILIZATION LOAD MANAGEMENT
MW MANAGEMENT
BLACK-START UNIT OPERATION
MECHANICAL INSPECTION
FUEL INSPECTION
MVAR MANAGEMENT
PATH MANAGEMENT
SWITCHING SEQUENCE INSPECTION
STATIC NON-BLACK-START MVAR UNIT OPERATION INSPECTION MAN-POWER DISPATCH
FAULT INSPECTION
STABILITY INSPECTION
CAPACITY INSPECTION
TRANSIENT VOLTAGE INSPECTION
17
Crank NBS Units System Restoration Check If a Tie Line Can Crank an NBS Unit Check If There Is a Path Between Them
Tie Line Utilization
Check If Tie Line Can Provide Enough Cranking Power
Negotiate for More Power Import
Load Management
Check If Enough Load Can Be Found
MW Management
Negotiate for Less Power Import
Path Management
18
Respond to Request System Restoration Respond to Tie Line Request Check If System Can Provide Enough Power
Tie Line Utilization
Negotiate for Less Power Export
Check Transmission Capacity
Load Management
Decide Priority of Tie Line
MW Management
Check Load Restoration Condition
MVAR Management
Check NBS Units Restart Condition
Path Management
19
Serve Load System Restoration Check if a Tie Line Can Serve Loads Check if There Are Transmission Paths
Tie Line Utilization
Check if Tie Line Can Provide Enough Power
Negotiate for More power Import
Load Management
Consider Using Tie Line Instead of System Generation
MW Management
Check if Enough Load Can Be Found
MVAR Management
Negotiate for Less Power Import
Path Management
20
Internal Units to be Cranked by TLi TLi
S1
TLe
21
Internal Units to Provide TLe - TLi TLi
S2
TLe
22
Cranking Paths Affected
TLi
TLe
CT
S3
23
Induced MWh Increase G2
G1
G3
24
Tie Line Utilization MWh Increase by S1 Increase from Earlier Startup of S1 Increase Induced by S1 MWh Decrease by S2 (S3) Decrease from Delayed Startup of S2 (S3) Decrease Induced by S2 (S3)
25
Test Subsystem CROMBY
PEACH BOTTOM
8 7 6 5
4 3 2 1
MUDDY RUN
7 6 5 4 3 2 1
8 9 10 11
CONOWINGO
26
System Generation Capability 3500
MW
3000 2500 2000
Without Peach Bottom
1500
With Peach Bottom
1000 500 0 0
100
200
300
400
500
600
Min after blackout
27
System Generation Capability MW
3500
3000
2500
0MW
1500
10MW
MW
2000
50MW & 100MW
1000
From Peach Bottom
500
0 0
100
200
300
400
500
600
Min after blackout
28
Generic Restoration Actions (GRAs) • start_black_start_unit (X) • find_path (X,Y) • energize_line (X) • pick_up_load (X) • synchronize (X,Y) • connect_tie_line (X) • crank_unit (X) • energize_busbar (X) 29
Using GRAs to Construct RBBs S1
BS
NBS B3
B1 B2 C3
C1 L2
L1 C2
30
Using GRAs to Construct RBBs • Find transmission path between BS & NBS • Start black-start unit BS • Build transmission path from busbar B1 to B3 and pick up loads for stabilization • Crank non-black-start unit NBS 31
Using RBBs & GRAs to Build Restoration Strategies BS1 B1
L1
C1a
C1b
L3 NBS
B2 B3 BS2
L2 C2a C2b
C3
32
Using RBBs & GRAs to Build Restoration Strategies • Select Two RBBs – RBB1: Use BS1 to energize B1 – RBB2: Use BS2 to energize B2
• Build RBB1 – Prepare load – Start BS unit – Energize bus 33
Using RBBs & GRAs to Build Restoration Strategies (Cont.) • Build RBB2 • Energize ring • Restart non-black-start unit NBS • Pick up loads along ring
34
Petri Net Algorithm to Optimize Sequence of GRAs TL1
Bus1 Line1-2
Bus2
L1
Line3-1
Bus3
Line2-3 L2
L3
35
Petri Net Model P1
P2
T1
P14
P8
P3
P15
T4
T2
T14
P4
P9
T5
T3
P21
P22
P17
P16 T15
T16
P25
36
Schulykill-Southwark Subsystem
37
Time to Complete GRAs Generic Restoration Action (GRA) Restart BSU Energize Busbar from BSU/busbar/line
Time (mins.) 15 5
Connect Tie Line
25
Crank a NBSU
15
Synchronize between Busbars/Lines
20
Pick up Load
10
38
Sequence of Actions for Schuylkill-Southwark ============================== Time (min.) Actions ----------------------------------------------------Restoration Building Block 1: 0 Connect BSU CT10 15 Energize bs2 from CT10 20 Energize bs3 from bs2 25 Energize bs4 from bs3 30 Crank NBSU ST3 from bs4 45 Synchronize ST3 with bs4 -----------------------------------------------------
39
Sequence of Actions for Schuylkill-Southwark ============================== Time (min.) Actions ----------------------------------------------------Restoration Building Block 2: 0 15 20 25 30 45
Connect BSU CT3-4 Energize bs9 from CT3-4 Energize bs10 from bs9 Energize bs11 from bs10 Crank NBSU ST1 from bs11 Synchronize ST1 with bs11
40
Sequence of Actions for Schuylkill-Southwark ----------------------------------------------65 Energize bs1 from bs2, bs14 from bs2, bs12 from bs3, bs5 from bs4, bs30 from bs9, bs8 from bs9, bs17 from bs11, bs15 from bs11, bs25 from bs10 70 Energize bs22 from bs1, bs19 from bs14, bs13 from bs12, bs7 from bs5, bs31 from bs39, bs21 from bs25, and synchronize bs14 with bs15 75 Energize bs32 from bs31, bs20 from bs21, bs23 from bs22, and connect bs7 with bs13, bs8 with bs7, and bs22 with bs21 80 Energize bs24 from bs23, bs26 from bs20 85 Energize bs27 from bs26 90 Energize bs28 from bs27 -----------------------------------------------------
41
Further Information • M. M. Adibi (Ed), Power System Restoration Methodologies & Implementation Strategies, IEEE Press, 2000. • J. Wu, C. C. Liu, and R. Chu, “A Petri Net Algorithm for Scheduling of Generic Restoration Actions,” IEEE Trans. Power Systems, Feb. 1997, pp. 69-76. • L. Fink, K. L. Liou, and C. C. Liu, “From Generic Restoration Actions to Specific Restoration Strategies,” IEEE Trans. Power Systems, May 1995, pp. 745-752. • K. L. Liou, C. C. Liu, and R. Chu, “Tie Line Utilization during Power System Restoration,” IEEE Trans. Power Systems, Feb. 1995, pp. 192-199. • C. C. Liu, K. L. Liou, et al., “Generation Capability Dispatch for Bulk Power System Restoration – A Knowledge-Based Approach,” IEEE Trans. Power Systems, Feb. 1993, pp. 316-325.
42
